A light-emitting diode (LED) is composed of a combination of an LED chip as an excitatory light source with a luminescent material and emits various luminescent colors depending on the combination. An LED chip which emits light in the ultraviolet to blue region and a luminescent material are used for a white LED light-emitting device which emits white light. For example, a combination of an LED chip which emits blue light with a mixture of luminescent materials is listed. As a luminescent material, it is common to use a luminescent material which emits light of yellow which is a complementary color of blue. A combination of an LED chip which emits blue light with a yellow luminescent material is called a pseudo-white LED light-emitting device. In addition to the device, a three-wavelength white LED light-emitting device formed by combining an LED chip which emits blue light and a luminescent material mixture containing a green luminescent material or a yellow luminescent material and a red luminescent material has been developed. However, when such a light-emitting device is used for illumination and backlight of a display, characteristics such as color rendering which shows the visibility of an object and color gamut showing a high hue value are insufficient. One of the causes of reduction of characteristics is that the emissive efficiency of a red luminescent material, particularly a deep red luminescent material which shows a deep red color is insufficient when using light in the ultraviolet to blue region as excitatory light.
As one of deep red luminescent materials, 3.5MgO.0.5MgF2.GeO2:Mn is known. For example, a white LED light-emitting device formed by combining a luminescent material mixture containing this luminescent material and a yttrium aluminum garnet (YAG) yellow luminescent material and a blue semiconductor light-emitting element is proposed in JP-A 2003-101081 (KOKAI). It is required that the luminescent material used for the white LED light-emitting device well absorbs the emission wavelength of the LED chip (i.e., an excitatory light source) and efficiently emits visible light. However, when the deep red luminescent materials are used, sufficient emissive efficiency is not obtained by excitatory light, particularly in a blue region and thus the emissive intensity is low. Therefore, there is also a problem in brightness of the white light-emitting device.